from turtle import *
from random import *

bgcolor(0, 0, 0)
ht()
speed(0)
pensize(2)
color(1, 1, 1)
r = 10
pu()
goto(0, -r)
pd()
acc_ext = 0
while True:
    color(choice([(0, 0, 0), (1, 1, 1)]))
    ext = random() * 90
    circle(r, ext)
    acc_ext += ext
    if acc_ext > 360:
        acc_ext = 0
        r += 3
        pu()
        goto(0, -r)
        seth(0)
        pd()
